This experimental temperature sensing system uses dual wavelength push-pull reflectometry and a thin-film band pass
filter deposited on an optical fiber end face. The system presents advantages over fiber Bragg grating sensors: it can use
the mature optical time domain reflectometry (OTDR) technology instead of expensive wavelength-selective technology;
it can probe the temperature in a small spot area; and it can be free from influences of disturbances along the optical fiber
or within the measuring system. Moreover, it preserves merits of optical fibers such as low transmission loss and
immunity to electromagnetic noise. The presented system has measurement accuracy of better than ±0.5°C.